XT_ALIGN changed to use ALIGN breaks iproute2

XT_ALIGN changed to use ALIGN breaks iproute2

[Andreas Henriksson]

Hello Alexey (and everyone else)!

You updated the kernel header include/linux/netfilter/x_tables.h
in torvalds/linux-2.6.git commit 42107f5009da223daa800d6da6904d77297ae829
with the comment "Use ALIGN() macro while I'm at it for same types.".

When this header was synced into iproute2 the build broke because the
ALIGN macro apparently only is defined in kernel headers.

(For iproute2 the problem was introduced in
8ecdcce08319d0e39b0d32c1d17db3f69d85a35c and found by Stephen
and worked around in 609ceb807deba8e23 and edaaa11e5a3cf2c9c1a39)

I'm guessing the problem in the iproute2 header sync is just a heads
up for what's going to happen when distributions updates their
system headers to match linux 2.6.33.


Could someone who knows how the userspace version of the kernel
headers are generated please find a suitable solution?

-- 
Andreas Henriksson

Re: XT_ALIGN changed to use ALIGN breaks iproute2

[Alexey Dobriyan]

On Tue, Mar 30, 2010 at 12:28 PM, Andreas Henriksson <andreas@fatal.se> wrote:
> You updated the kernel header include/linux/netfilter/x_tables.h
> in torvalds/linux-2.6.git commit 42107f5009da223daa800d6da6904d77297ae829
> with the comment "Use ALIGN() macro while I'm at it for same types.".
>
> When this header was synced into iproute2 the build broke because the
> ALIGN macro apparently only is defined in kernel headers.
>
> (For iproute2 the problem was introduced in
> 8ecdcce08319d0e39b0d32c1d17db3f69d85a35c and found by Stephen
> and worked around in 609ceb807deba8e23 and edaaa11e5a3cf2c9c1a39)
>
> I'm guessing the problem in the iproute2 header sync is just a heads
> up for what's going to happen when distributions updates their
> system headers to match linux 2.6.33.
>
>
> Could someone who knows how the userspace version of the kernel
> headers are generated please find a suitable solution?

We can export ALIGN to userspace, but the name is so generic,
so it's not clear what breakage more risky.

XT_ALIGN is a macro so breakage will appear only when it's used,
not when header is included directly or indirectly.

We have tc, iptables, both carry their own copy of headers, what else?

Right now, I'd say, do nothing, and iptables will carry fixlet as in tc,
eventually.

Re: XT_ALIGN changed to use ALIGN breaks iproute2

[Ben Hutchings]

On Tue, 2010-03-30 at 16:15 +0300, Alexey Dobriyan wrote:
> On Tue, Mar 30, 2010 at 12:28 PM, Andreas Henriksson <andreas@fatal.se> wrote:
> > You updated the kernel header include/linux/netfilter/x_tables.h
> > in torvalds/linux-2.6.git commit 42107f5009da223daa800d6da6904d77297ae829
> > with the comment "Use ALIGN() macro while I'm at it for same types.".
> >
> > When this header was synced into iproute2 the build broke because the
> > ALIGN macro apparently only is defined in kernel headers.
> >
> > (For iproute2 the problem was introduced in
> > 8ecdcce08319d0e39b0d32c1d17db3f69d85a35c and found by Stephen
> > and worked around in 609ceb807deba8e23 and edaaa11e5a3cf2c9c1a39)
> >
> > I'm guessing the problem in the iproute2 header sync is just a heads
> > up for what's going to happen when distributions updates their
> > system headers to match linux 2.6.33.
> >
> >
> > Could someone who knows how the userspace version of the kernel
> > headers are generated please find a suitable solution?
> 
> We can export ALIGN to userspace, but the name is so generic,
> so it's not clear what breakage more risky.

Right.

> XT_ALIGN is a macro so breakage will appear only when it's used,
> not when header is included directly or indirectly.
> 
> We have tc, iptables, both carry their own copy of headers, what else?
> 
> Right now, I'd say, do nothing, and iptables will carry fixlet as in tc,
> eventually.

Why should every user-space consumer have to fix this up?  We've been
through this with ethtool.h in the past (wrong type names); please don't
repeat that mistake.

Note that <linux/kernel.h> is exported and could be changed to define a
macro named e.g. __KERNEL_ALIGN() for user-space.

Ben.

-- 
Ben Hutchings, Senior Software Engineer, Solarflare Communications
Not speaking for my employer; that's the marketing department's job.
They asked us to note that Solarflare product names are trademarked.

Re: XT_ALIGN changed to use ALIGN breaks iproute2

[Stephen Hemminger]

On Tue, 30 Mar 2010 16:01:18 +0100
Ben Hutchings <bhutchings@solarflare.com> wrote:

> On Tue, 2010-03-30 at 16:15 +0300, Alexey Dobriyan wrote:
> > On Tue, Mar 30, 2010 at 12:28 PM, Andreas Henriksson <andreas@fatal.se> wrote:
> > > You updated the kernel header include/linux/netfilter/x_tables.h
> > > in torvalds/linux-2.6.git commit 42107f5009da223daa800d6da6904d77297ae829
> > > with the comment "Use ALIGN() macro while I'm at it for same types.".
> > >
> > > When this header was synced into iproute2 the build broke because the
> > > ALIGN macro apparently only is defined in kernel headers.
> > >
> > > (For iproute2 the problem was introduced in
> > > 8ecdcce08319d0e39b0d32c1d17db3f69d85a35c and found by Stephen
> > > and worked around in 609ceb807deba8e23 and edaaa11e5a3cf2c9c1a39)
> > >
> > > I'm guessing the problem in the iproute2 header sync is just a heads
> > > up for what's going to happen when distributions updates their
> > > system headers to match linux 2.6.33.
> > >
> > >
> > > Could someone who knows how the userspace version of the kernel
> > > headers are generated please find a suitable solution?
> > 
> > We can export ALIGN to userspace, but the name is so generic,
> > so it's not clear what breakage more risky.
> 

I put a hack in m_xt.c to keep iproute2 building.
But this is a temporary workaround until you guys figure out the
right answer.

-- 

Re: XT_ALIGN changed to use ALIGN breaks iproute2

[Patrick McHardy]

Stephen Hemminger wrote:
> On Tue, 30 Mar 2010 16:01:18 +0100
> Ben Hutchings <bhutchings@solarflare.com> wrote:
> 
>> On Tue, 2010-03-30 at 16:15 +0300, Alexey Dobriyan wrote:
>>> On Tue, Mar 30, 2010 at 12:28 PM, Andreas Henriksson <andreas@fatal.se> wrote:
>>>> You updated the kernel header include/linux/netfilter/x_tables.h
>>>> in torvalds/linux-2.6.git commit 42107f5009da223daa800d6da6904d77297ae829
>>>> with the comment "Use ALIGN() macro while I'm at it for same types.".
>>>>
>>>> When this header was synced into iproute2 the build broke because the
>>>> ALIGN macro apparently only is defined in kernel headers.
>>>>
>>>> (For iproute2 the problem was introduced in
>>>> 8ecdcce08319d0e39b0d32c1d17db3f69d85a35c and found by Stephen
>>>> and worked around in 609ceb807deba8e23 and edaaa11e5a3cf2c9c1a39)
>>>>
>>>> I'm guessing the problem in the iproute2 header sync is just a heads
>>>> up for what's going to happen when distributions updates their
>>>> system headers to match linux 2.6.33.
>>>>
>>>>
>>>> Could someone who knows how the userspace version of the kernel
>>>> headers are generated please find a suitable solution?
>>> We can export ALIGN to userspace, but the name is so generic,
>>> so it's not clear what breakage more risky.
> 
> I put a hack in m_xt.c to keep iproute2 building.
> But this is a temporary workaround until you guys figure out the
> right answer.

I can't think of anything but to restore the XT_ALIGN macro.
We could add a XT_ALIGN definition to xtables.h, but that might
still leave problems for other users.

Alexey, do you have any better suggestions?